Li Na of China hits a return to Ana Konjuh of Croatia during their singles match in the first round of the Australian Open in Melbourne. Photo: Reuters

A clinical Serena Williams and China’s Li Na showed their intent on an eventful first day at the Australian Open on Monday.

Top-ranked Williams extended her winning streak to 23 matches by putting Australian wild-card entry teenager Ashleigh Barty to the sword 6-2, 6-1, while Li, last year’s runner-up, raced through her opener against 16-year-old Ana Konjuh of Croatia 6-2, 6-0.

“I think it was very lucky we played today. Tomorrow [Tuesday] will be worse,” said Li referring to the heat. She said she had moved her practice for Tuesday, when temperatures are forecast to soar, to an earlier slot. “I didn’t want to kill myself on the court,” she said.